1. Field of the Invention
The present invention generally relates to an image forming device. More specifically, the present invention relates to an image forming device connected to a data processing device, and equipped with a printer unit, a copying unit which makes copies of the documents printed in the printer unit, and a document transport device for transporting printed documents from the printer unit to the copying unit.
2. Description of the Related Art
Printers which print out character and image data sent from data processing devices such as personal computers are widely known. One problem with these types of printers has been that a significant amount of time is needed to print a large number of copies, especially when compared with the time that it takes a copying machine to do the same job.
An image forming device which attempts to solve this problem is disclosed in Japanese Unexamined Patent Application No. 5-107987 (1995). This image forming device is a combination of a copying unit and a printer unit, and is connected to a data processing device. The image data output from the data processing device is printed out by the printer unit, and the printed documents are then transported to an document mounting unit on the copying unit. The documents on the mounting unit are then sequentially transported to a document reading unit, and then read and copied as instructed. Because the documents printed in the printer unit are used as the originals in the copying unit, a large number of copies can be made at a relatively high speed.
In the above-described image forming device, the document mounting unit on the copying unit is located on the upper portion of the main body of the image forming device. In addition, because the documents from the printer unit are transported to the document mounting unit on the copying unit, the printer unit is also located on the upper portion of the main body of the image forming device, and adjacent to the document mounting unit.
However, because the upper portion of the main body of the image forming device also includes an document transport device for the copying unit, there is no space for a maintenance access port. For instance, if a large-sized toner cartridge is required in the copying unit, it is very convenient if this cartridge can be replaced through a maintenance access port in the upper portion of the device. However, because there is no space for an access port in the upper portion of the main body of this image forming device, a large-sized toner cartridge must be replaced through an access door in the side of the main body, which can be quite inconvenient.
In addition, this lack of space makes it difficult to clear paper jams which may occur when paper in the printer unit is discharged from the printer unit to the document mounting unit on the copying unit.
Another problem with this prior art device is that the printer unit is incapable of receiving image data from the data processing device while the copying unit is in operation, even though the printer unit is not operating. Thus, the operational efficiency of both the image forming device and the data processing device is lowered. Likewise, the operation panel of the copying unit is unable to receive instructions from the user while the printer unit is in operation, even though the copying unit is not operating. This also lowers the operational efficiency of the image forming device.
Furthermore, if the document transport device employed in the of copying unit is a RDH (returnable document handler) type and not equipped with a document sorter, when the number of copies is two or more, the copied originals are returned to the document mounting unit when copying is completed. In an ADF (automatic document feeder) type of copying unit that is equipped with a document sorter, the copied originals are discharged to the document discharge unit. However, regardless of which type of copying unit is used, the positions to which the copied originals are finally discharged are fixed, and thus the discharged originals could be mistakenly mixed with other originals which other users forgot to pick up. In particular, this problem could occur quite frequently when the image process control data is transmitted remotely from a plurality of data processing devices. For example, when originals are on the document mounting unit and other operators have forgotten to pick them up, documents printed in the printer unit will be transported to the document mounting unit and be mixed with them.